A common problem associated with high temperature hydrocarbon reactions is coke formation in the furnace. Coke deposits can prevent proper heat transfer in process tubes and increase the pressure drop through the furnace. Coke build-up necessitates periodic process shutdowns for removal of the deposits. Therefore, it is very desirable to inhibit coke deposits by use of an additive which can inhibit coke formation.
The coke inhibitor can be applied as coatings to metal tube surfaces prone to deposit formation. Alternatively, the coke inhibitor can be added to the hydrocarbon feedstock. In the latter instance, the coke inhibitor is generally either dissolved or suspended in a cold inlet stream.
Recent developments have produced relatively effective coke inhibiting additives which are ordinarily solids, inorganic-based and insoluble in the feedstock. Thus, an effective apparatus is needed for dispersing these agents in the feedstock. Several problems are evident, especially for hot point addition in the feed. Solid additives must generally be introduced as a solution or suspension in a liquid carrier. Solvent evaporation due to heat from the feed can result in deposits and plugging in the injection apparatus. Liquid impingement of the liquid carrier on hot metal surfaces can promote metal fatigue in the lines. Consequently, the liquid additive must be cool at the addition point yet the solvent must be completely evaporated before hot surfaces are encountered.
U.S. Pat. No. 4,647,367 to Urban et al. discloses metallic phthalocyanine anti-fouling agents for prevention of coke deposits in high temperature petroleum reactors.
U.S. Pat. No. 3,034,726 to Peras describes a device for atomizing a liquid using a pressurized gas. The device includes an inner tube for the liquid terminating in a nozzle and an annular chamber for the gas at the nozzle. The device also includes a heating means for vaporizing the atomized liquid.
U.S. Pat. No. 3,589,611 to Jones, Jr. describes a distributor pipe for injecting fluids into a vessel wherein the distributor includes a complete cooling jacket for the portion of the tube exposed to the interior of the vessel.
U.S. Pat. No. 3,408,007 to Raichle et al. describes an apparatus for atomizing highly viscous materials such as a molten polymer with a gas. The apparatus includes a heated nozzle with a conical discharge end for the liquid. Exterior to the discharge end is a passage for the gas with a narrow frustoconical aperture.
U.S. Pat. No. 1,652,372 to O'Brien describes an atomizer comprising two overlapping tubular members forming an annular channel for liquid and an inner passage for air or gas under pressure. The atomizer terminates in a conical mixing chamber having a nozzle outlet.
U.S. Pat. No. 3,527,832 to Pamphilis et al. describes a special baffled collection manifold which is used on steam cracker furnace outlet tubes to lessen the tendency of steam cracker effluents to coke downstream from the furnace.
U.S. Pat. No. 5,039,391 to Reid et al. discloses boron containing compounds and dihydroxybenzenes to reduce coking in coker furnaces.
U.S. Pat. No. 3,843,744 to Kramer et al. describes a method for controlling and diminishing the formation of coke on the walls of reactors in the pyrolysis of hydrocarbons to acetylene which comprises injection of steam and/or inert gas at one or more critically located points downstream from the feed injection.
U.S. Pat. No. 5,000,836 to Forester discloses molybdenum and boron compounds for inhibiting coke formation in pyrolytic furnaces.